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Toward a better understanding of microbiologically influenced corrosion caused by sulfate reducing bacteria

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Journal of Materials Science & Technology 2019年第4期35卷 631-636页

作者： Tingyue Gu ru jia Tuba Unsal Dake Xu Department of Chemical and Biomolecular Engineering Institute for Corrosion and Multiphase TechnologyOhio University School of Materials Science and Engineering Northeastern University

Sulfate reducing bacteria(SRB) are often the culprits of microbiologically influenced corrosion(MIC) in anoxic environments because sulfate is a ubiquitous oxidant. MIC of carbon steel caused by SRB is the most intensively investigated topic in MIC because of its practical importance. It is also because biogenic sulfides complicate mechanistic SRB MIC studies, making SRB MIC of carbon steel is a long-lasting topic that has generated considerable confusions. It is expedient to think that biogenic H_2S secreted by SRB acidifies the broth because it is an acid gas. However, this is not true because endogenous H_2S gets its H^+ from organic carbon oxidation and the fluid itself in the first place rather than an external source. Many people believe that biogenic H_2S is responsible for SRB MIC of carbon steel. However, in recent years,well designed mechanistic studies provided evidence that contradicts this misconception. Experimental data have shown that cathodic electron harvest by an SRB biofilm from elemental iron via extracellular electron transfer(EET) for energy production by SRB is the primary cause. It has been demonstrated that when a mature SRB biofilm is subjected to carbon source starvation, it switches to elemental iron as an electron source and becomes more corrosive. It is anticipated that manipulations of EET related genes will provide genetic-level evidence to support the biocathode theory in the future. This kind of new advances will likely lead to new gene probes or transcriptomics tools for detecting corrosive SRB strains that possess high EET capabilities.

关键词： Sulfate-reducing bacteria(SRB) Microbiologically influenced corrosion(MIC) Carbon steel Extracellular electron transfer

Test analysis of detection of damage to a complicated spatial model structure

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Acta Mechanica Sinica 2011年第3期27卷 399-405页

作者： Long-He Xu Zhong-Xian Li jia-ru Qian School of Civil Engineering Beijing Jiaotong University 100044 Beijing China School of Civil Engineering Tianjin University 300072 Tianjin China Department of Civil Engineering Tsinghua University 100084 Beijing China

A two-stage damage detection approach is proposed and experimentally demonstrated on a complicated spatial model structure with a limited number of measurements. In the experiment,five known damage patterns,including 3 brace damage cases and 2 joint damage cases,were simulated by removing braces and weakening beam鈥揷olumn connections in the structure. The limited acceleration response data generated by hammer impact were used for system identification,and modal parameters were extracted by using the eigensystem realization algorithm. In the first stage,the possible damaged locations are determined by using the damage index and the characteristics of the analytical model itself,and the extent of damage for those substructures identified at stage I is estimated in the second stage by using a second-order eigen-sensitivity approximation method. The main contribution of this paper is to test the two-stage method by using the real dynamic data of a complicated spatial model structure with limited sensors. The analysis results indicate that the two-stage approach is ableto detect the location of both damage cases,only the severity of brace damage cases can be assessed,and the reasonable analytical model is critical for successful damage detection.

关键词： Damage detection. Complicated structure. Two-stage approach - Eigen-sensitivity analysis. Joint dam- age

Effects of d-Phenylalanine as a biocide enhancer of THPS against the microbiologically influenced corrosion of C1018 carbon steel

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Journal of Materials Science & Technology 2019年第1期35卷 109-117页

作者： Jin Xu ru jia Dongqing Yang Cheng Sun Tingyue Gu Department of Chemical and Biomolecular Engineering Institute for Corrosion and Multiphase Technology Ohio University Environmental Corrosion Center Institute of Metal Research Chinese Academy of Sciences

Microbiologically influenced corrosion(MIC) is caused by biofilms such as those of sulfate reducing bacteria(SRB). To mitigate MIC, biocide treatment is often needed. Tetrakis(hydroxymethyl) phosphonium sulfate(THPS) is an environmentally friendly biocide that is often used in the oil and gas industry. However, its prolonged use leads to biocide resistance, leading to dosage escalation. A biocide enhancer can be used to slow down the trend. In recent years, d-amino acids have been investigated as an enhancer for THPS and other biocides. Published works used anaerobic vials and flow devices, which could not reveal the real-time changes of the biocide treatment on corrosion. In this work, it was proven that the biocide enhancement effects of d-Phenylalanine(d-Phe) on THPS against the Desulfovibrio vulgaris biofilm on C1018 carbon steels could be assessed in real time using linear polarization resistance and electrochemical impedance spectroscopy to collaborate sessile cell count, weight loss and pitting depth data. The results showed that 500 ppm(w/w) d-Phe effectively enhanced 80 ppm THPS against MIC by the D. vulgaris(a corrosive SRB) biofilm. The sessile cell count and pit depth were all reduced with the enhancement of d-Phe.

关键词： D-amino acid THPS SRB Corrosion Biofilm

Effect of vibration on seepage feeding during low-pressure casting of ZL205A alloy

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China Foundry 2019年第1期16卷 40-45页

作者： ru-jia Wang Shi-ping Wu Wei Chen School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China

Appropriate vibration can promote the feeding capacity of gravity casting, but the effect of vibration on the feeding of low-pressure casting is not clear. The effect of vibration on the seepage feeding of ZL205A alloy was investigated by vibration casting experiment and physical simulation. The aqueous solution of sodium carboxymethyl cellulose(CMC) with the same rheological characteristic of metal melt was used. The results show that vibration can improve the feeding capacity and reduce shrinkage defects of ZL205A alloy in lowpressure casting. The orthogonal physical simulation experiments indicate that vibration with low frequency and great exerted force can significantly improve the seepage velocity of non-Newtonian fluid with solid particles in porous medium. The seepage phenomenon in CMC solution shows that vibration can change the structure of accumulated particles at the seepage entrance, and thus open the blocked feeding channel. The numerical simulation of one-dimensional semisolid fluid seepage reveals that vibration can form a wave field in the porous medium, which can reduce the adhesion force between fluid and capillary wall and destroy the boundary layer of fluid, and thus promote the seepage velocity.

关键词： mechanical vibration physical simulation seepage ZL205A alloy

MMSE based joint Tomlinson-Harashima source and linear relay precoder design in non-regenerative MIMO relay system

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The Journal of China Universities of Posts and Telecommunications 2012年第4期19卷 56-63页

作者： LI Nan CHEN Peng HE Zhi-qiang LIN jia-ru Key Lab of Universal Wireless Communications Ministry of EducationBeijing University of Posts and TelecommunicationsBeijing 100876China

This paper proposes a joint nonlinear transceiver design scheme based on minimum mean square error （MMSE） criterion for non-regenerative multiple input multiple output （MIMO） relay system. The proposed scheme decomposes the error covariance matrix, reformulates the original joint design problem as two separate optimization problems, and then provides a closed-form solution with only local channel state information （CSI） available at the source and destination. Performance evaluation shows that the proposed scheme significantly outperforms linear schemes, and has a competitive performance compared with existing global CSI based nonlinear schemes, both iterative and non-iterative.

关键词： MIMO non-regenerative relay joint transceiver design Tomlinson-Harashima precoding (THP) MMSE

Ad-hoc network DOA tracking via sequential Monte Carlo filtering

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The Journal of China Universities of Posts and Telecommunications 2007年第1期14卷 12-15页

作者： GUO Li GUO Yan LIN jia-ru LI Ning Key Laboratory of Information Processing and Intelligent Technology BeijingUniversity of Posts and Telecommunications Beijing 100876 China Institute of Science PLA University of Science and TechnologyNanjing 210007 China

A novel sequential Monte Carlo （SMC） algorithm is provided for the multiple maneuvering Ad-hoc network terminals direction of arrival （DOA） tracking. A nonlinear mobility and observation model is adopted, which can describe the motion features of the Ad-hoc network terminal more practically. The algorithm does not need any additional measurement equipment. Simulation result shows its significant tracking accuracy.

关键词： Bayesian inference Ad-hoc network DOA tracking,SMC

Performance analysis of ARQ schemes with code combining over Nakagami-m fading channel

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The Journal of China Universities of Posts and Telecommunications 2009年第5期16卷 14-19页

作者： XU Wen-bo NIU Kai LIN jia-ru HE Zhi-qiang School of Information and Telecommunication Engineering Beijing University of Posts and Telecommunications Beijing 100876 China

This article investigates the performance of hybrid automatic repeat request （HARQ） with code combining over the ideally interleaved Nakagami-m fading channel. Two retransmission protocols with coherent equal gain code combining are adopted, where the entire frame and several selected portions of the frame are repeated in protocols I and II, respectively. Protocol II could be viewed as a generalization of the recently proposed reliability-based HARQ. To facilitate performance analysis, an approximation of the product of two independent Nakagami-m distributed random variables is first developed. Then the approximate analysis is utilized to obtain exact frame error probability （FEP） for protocol I, and the upper bound of the FEP for protocol II. Furthermore, the throughput performance of both two protocols is presented. Simulation results show the reliability of the theoretical analysis, where protocol II outperforms protocol I in the throughput performance due to the reduced amount of transmitted information.

关键词： code combining HARQ Nakagami-m fading performance analysis

A non-invasive diagnostic method of cavity detuning based on a convolutional neural network

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Nuclear Science and Techniques 2022年第7期33卷 25-35页

作者： Liu-Yuan Zhou Hao Zha jia-ru Shi jia-Qi Qiu Chuan-Jing Wang Yun-Sheng Han Huai-Bi Chen Department of Engineering Physics Tsinghua UniversityBeijing100084China Key Laboratory of Particle and Radiation Imaging Tsinghua UniversityBeijing100084China

As modern accelerator technologies advance toward more compact sizes,conventional invasive diagnostic methods of cavity detuning introduce negligible interference in measurements and run the risk of harming structural *** overcome these difficulties,this study developed a non-invasive diagnostic method using knowledge of scattering parameters with a convolutional neural network and the interior point *** construction and training of the neural network led to remarkable results on three typical acceleration structures:a 13-cell S-band standing-wave linac,a 12-cell X-band traveling-wave linac,and a 3-cell X-band RF *** trained networks significantly reduced the burden of the tuning process,freed researchers from tedious tuning tasks,and provided a new perspective for the tuning of side-coupling,semi-enclosed,and total-enclosed structures.

关键词： Cavity detuning Convolutional neural network Equivalent circuit

Resource allocation for the cluster-based cooperative multicast in OFDM-based cognitive radio systems

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The Journal of China Universities of Posts and Telecommunications 2013年第4期20卷 1-7,33页

作者： ZHANG Shuang-lu XU Wen-jun LI Sheng-yu LIN jia-ru School of Information and Communication Engineering Beijing University of Posts and Telecommunications

This paper investigates the resource allocation problem for the cluster-based cooperative multicast in orthogonal frequency division multiplexing （OFDM）-based cognitive radio （CR） systems. Aiming at maximizing the system sum rate, an efficient clustering scheme is proposed. It begins with the clustering phase where secondary users （SUs） with good channel conditions are selected as cluster heads, while others decide to which cluster they belong. When the clusters are organized, it turns to a two-stage data transmission phase： in stage 1, the secondary＇ base station （BS） transmits data to the cluster heads; in stage 2, the cluster heads forward the received data to their cluster members. Based on this scheme, a joint subcarrier and power allocation algorithm is proposed. Simulation results show that the proposed scheme significantly outperforms the conventional multicast （CM） as well as the multiple description coding multicast 0VIDCM） in terms of the system sum rate.

关键词： cooperative multicast cognitive radio OFDM cluster